Metal Gear Solid V: Ground Zeroes is a relatively short game, but this is to be expected since Ground Zeroes was meant to act as a prequel to Metal Gear Solid V: The Phantom Pain that could see a release in 2015. This in no way detracts from the game despite it being a short game as reviews of Ground Zeroes have revealed that it is a pretty good game.
That being said, if you’re playing Ground Zeroes and were planning on getting Phantom Pain, you might want to keep your Ground Zeroes save file because according to Konami, it seems that the save file of your Ground Zeroes game could affect your Phantom Pain game. One of the examples they gave is that by loading your Ground Zeroes save file onto Phantom Pain will have all the POWs you saved in Ground Zeroes appear in the Mother Base.
That feature was mentioned in the past, but Konami adds that there will also be unique characters appearing in Phantom Pain, depending on your Ground Zeroes save file. We’re not sure what sort of criteria one must have on their save file or if there must be certain missions/achievements done in Ground Zeroes in order to unlock certain characters, but either way it will be worth your while to keep the save file around.
Unfortunately Konami does not mention what sort of unique characters we can expect, but if you’re the type of gamer who must have every achievement and unlock every character, then perhaps this is something worth keeping in mind when you play Ground Zeroes.